Bug Description

When using a custom provider with custom_providers configured (including per-model context_length), the compression model feasibility check (_check_compression_model_feasibility) incorrectly resolves the auxiliary compression model context as 256K (the DEFAULT_FALLBACK_CONTEXT), even when the model and provider are identical to the main model which correctly resolves to the configured context (e.g. 1M).

This causes a false warning at startup about lowering the compression threshold.

Root Cause

_check_compression_model_feasibility() in run_agent.py calls get_model_context_length() without passing the custom_providers parameter. This skips step 0b of the resolution order, which is where per-model context_length overrides from custom_providers config are applied.

Compare the two call sites in run_agent.py:

Without custom_providers, the resolution chain for unknown custom endpoints short-circuits at step 2 in get_model_context_length(): it tries the /models endpoint, gets no context_length metadata back, and immediately returns DEFAULT_FALLBACK_CONTEXT (256K) without ever reaching the hardcoded defaults or custom_providers entries.

Steps to Reproduce

1. Configure a custom provider with custom_providers including a per-model context_length (e.g. 1,000,000)
2. Set compression.threshold high enough that the main model threshold exceeds 256K (e.g. 0.85 × 1M = 850K)
3. Ensure the auxiliary compression model resolves to the same custom provider/model
4. Start Hermes — observe the false warning about 256K compression context

Fix

Add custom_providers resolution to _check_compression_model_feasibility() so it passes the parameter through to get_model_context_length(), matching the main-model path:

# Resolve custom_providers for the compression model
_aux_custom_providers = []
try:
    from hermes_cli.config import load_config, get_compatible_custom_providers
    _cfg = load_config()
    _aux_custom_providers = get_compatible_custom_providers(_cfg)
except Exception:
    pass

aux_context = get_model_context_length(
    aux_model,
    base_url=aux_base_url,
    api_key=aux_api_key,
    config_context_length=...,
    provider=...,
    custom_providers=_aux_custom_providers,  # was missing
)

Affected Version

Observed on Hermes Agent main branch (post v0.12.x). The custom_providers parameter was added to get_model_context_length() for the main model path but the compression feasibility check was not updated to match.

Environment

• OS: Linux (Arch-based)
• Provider: custom endpoint with custom_providers config